Much activity has been directed towards finding a suitable adsorbent for removing caffeine from an aqueous coffee extract. Activated carbon has long been known as a caffeine adsorbent but use of such carbon has been limited by the concurrent adsorption of non-caffeine coffee solids during decaffeination, making the process uneconomical. Several processes are directed to overcoming the problem as recently disclosed in commonly assigned U.S. Pat. App. Ser. Nos. 076,717 abandoned and 279,498 abandoned both to Pfluger et al. as well as in European Pat. App. No. 79102 822.8/Document No. 0,008,398. Both Pfluger et al. applications describe treating the activated carbon with a solution of one or more carbohydrates prior to decaffeinating an aqueous coffee extract.
Decaffeination with activated carbon, even by the methods disclosed above, is still hampered by the tenacity with which the caffeine adsorbs to the activated carbon, which tenacity makes regeneration of said carbon extremely difficult. Two recent disclosures, U.S. Pat. No. 4,298,736 to Katz et al. and commonly assigned U.S. Pat. App. Ser. No. 306,276 abandoned to Katz et al., describe effective techniques for removing adsorbed caffeine from activated carbon. The inventions call for contacting activated carbon containing both caffeine and non-caffeine solids with an organic acid or aqueous solution of an organic acid or an alcohol. The effect of the contact is to strip the activated carbon of substantially all material contained thereon. Though the caffeine is indeed removed, the resulting solution is low in caffeine purity; roughly 25% by weight of the total solids in solution is caffeine. The low purity renders the mixture difficult to refine. Additionally, the non-caffeine solids are rendered somewhat unusable by the refining process and can not generally be re-adsorbed onto the activated carbon bed.
It is an object of the present invention to separately recover the caffeine and non-caffeine solids adsorbed on activated carbon. A further object is to recover the caffeine in relatively pure form. Another object of the present invention is to recover the non-caffeine solids in a form suitable for re-adsorption onto the activated carbon.